1. Field of the Invention
The present invention relates to an image reading apparatus and an image forming apparatus capable of efficiently irradiating a document with light from a light source.
2. Description of the Related Art
An image reading apparatus including an illuminator for irradiating a document with light, a mirror for forming an optical path by reflecting the light reflected by the document, an imaging lens for imaging this light and a CCD (Charge Coupled Device) for reading an image of a document from the imaged light is known as an image reading apparatus for optically reading a document image.
An image reading apparatus using a light guide is also known. The light guide is arranged in an optical path between a light source and a document and a light emitting surface thereof is obliquely and flatly cut. The light totally reflected by the light emitting surface is totally reflected in the light guide and, thereafter, emitted toward an object to be irradiated such as a document without being reflected by any surface of the light guide.
However, since only total reflection is utilized and the light emitting surface is a flat surface in the above light guide, much light is irradiated outside an effective irradiation range. Further, the light is poorly condensed to the object to be irradiated. Furthermore, since the light guide needs to be arranged at a position distant from a reading position in order to guide the totally reflected light to the object to be irradiated, there has been a problem of being difficult to downsize the apparatus.